Gem-Knight Ruby [BLMM-EN136] Ultra Rare

'Gem-Knight Garnet' + 1 'Gem-Knight' monsterMust first be Fusion Summoned with the above Fusion Material Monsters. Once per turn: You can Tribute 1 face-up 'Gem-' monster; this card gains ATK equal to the Tributed monster's ATK on the field, until the End Phase. If this card attacks a Defense Position monster, inflict piercing Battle Damage to your opponent.